TRANSMIT (TX) INTERFERENCE CANCELLER AND POWER DETECTOR

• US 20140269991A1
• Filed: 03/14/2013
• Published: 09/18/2014
• Est. Priority Date: 03/14/2013
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Aparin, Vladimir
• Granted Patent: US 8,942,314 B2
• Time in Patent Office: Days
• US Class Current: 375/297
• CPC Class Codes: H04B 1/0475 with means for limiting noise, interference or distortion H04B1/0483 takes precedence
• CPC Class Codes: H04B 1/525 with means for reducing leakage of transmitter signal into the receiver
• CPC Class Codes: H04B 15/04 the interference being caused by substantially sinusoidal oscillations, e.g. in a receiver or in a tape-recorder
• CPC Class Codes: H04B 15/06 by local oscillators of receivers

Abstract

A method for Tx interference cancellation and power detection in a wireless device is described. A portion of a Tx output signal is down-converted to generate a feedback signal. A reconstructed interference signal and a weight are generated based on the feedback signal. A Tx power level is detected based on the weight. The reconstructed interference signal is subtracted from the Tx output signal.

Claims

1. A method for Tx interference cancellation and power detection in a wireless device, the method comprising:

down-converting a portion of a Tx output signal to generate a feedback signal;

generating a reconstructed interference signal and a weight based on the feedback signal;

detecting a Tx power level based on the weight; and

subtracting the reconstructed interference signal from the Tx output signal.

2. The method of claim 1, wherein generating the reconstructed interference signal and the weight, detecting the Tx power level, and subtracting the reconstructed interface signal are performed in the digital domain.

3. The method of claim 1, wherein the portion of the Tx output signal is down-converted using a frequency from a Tx local oscillator.

4. The method of claim 1, further comprising amplifying a baseband Tx signal using a driver amplifier coupled to a power amplifier to obtain the Tx output signal.

5. The method of claim 4, wherein the weight is based on signal gain between the baseband Tx signal and the Tx output signal.

6. The method of claim 1, wherein the weight comprises a real weight component and an imaginary weight component, and wherein the real weight component is A sin(φ

)/2 and the imaginary weight component is A cos(φ

)/2.

7. The method of claim 1, wherein detecting the Tx power level comprises adding together a squared real weight component with a squared imaginary weight component to obtain the Tx power level.

8. The method of claim 1, wherein the Tx power level is detected using root mean square calculations on the weight.

9. The method of claim 1, wherein subtracting the reconstructed interference signal from the Tx output signal further comprises subtracting the reconstructed interference signal from a baseband Tx signal prior to up-converting and amplifying the baseband transmit signal.

10. The method of claim 1, further comprising adjusting an output power of the wireless device based on the Tx power level.

11. The method of claim 10, wherein adjusting the output power of the wireless device comprises adjusting amplification of a power amplifier.

12. The method of claim 10, wherein adjusting the output power comprises:

matching the detected Tx power level to a look-up table; and

obtaining the output power from the look-up table.

13. The method of claim 1, wherein the reconstructed interference signal and the weight are generated reusing least mean-squared cancellers on the wireless device.

14. The method of claim 13, wherein the least mean-squared cancellers isolate a desired Tx signal of the feedback signal.

15. The method of claim 14, wherein the least mean-squared cancellers remove the desired Tx signal from the feedback signal, leaving only noise and interference in the reconstructed interference signal.

16. The method of claim 1, further comprising applying a phase shift to the reconstructed interference signal prior to subtracting the reconstructed interference signal from the Tx output signal.

17. An apparatus for Tx interference cancellation and power detection, the apparatus comprising:

a feedforward path configured to generate a Tx output signal from a baseband Tx signal; and

a feedback loop comprising;

a Tx interference canceller/power detector that generates a reconstructed interference signal and a weight from a feedback signal and that detects a Tx power level based on the weight; and

a summer that subtracts the reconstructed interference signal from the Tx output signal.

18. The apparatus of claim 17, wherein the Tx interference canceller/power detector and the summer operate in the digital domain.

19. The apparatus of claim 17, wherein a portion of the Tx output signal is used as the feedback signal.

20. The apparatus of claim 17, wherein the feedback signal is down-converted using a frequency from a Tx local oscillator.

21. The apparatus of claim 17, wherein the weight is based on signal gain between the baseband Tx signal and the Tx output signal.

22. The apparatus of claim 17, wherein the weight comprises a real weight component and an imaginary weight component, and wherein the real weight component is A sin(φ

)/2 and the imaginary weight component is A cos(φ

)/2.

23. The apparatus of claim 17, wherein the Tx interference canceller/power detector detects the Tx power level by adding together a squared real weight component with a squared imaginary weight component.

24. The apparatus of claim 17, wherein the Tx interference canceller/power detector detects the Tx power level by using root mean square calculations on the weight.

25. The apparatus of claim 17, further comprising a modem that receives the Tx power level, wherein the modem adjusts an output power of the wireless device based on the Tx power level.

26. The apparatus of claim 25, wherein the modem matches the detected Tx power level to a look-up table to determine the output power.

27. A computer-program product for Tx interference cancellation and power detection in a wireless device, the computer-program product comprising a non-transitory computer-readable medium having instructions thereon, the instructions comprising:

code for causing the wireless device to down-convert a portion of a Tx output signal to generate a feedback signal;

code for causing the wireless device to generate a reconstructed interference signal and a weight based on the feedback signal;

code for causing the wireless device to detect a Tx power level based on the weight; and

code for causing the wireless device to subtract the reconstructed interference signal from the Tx output signal.

28. The computer-program product of claim 27, wherein the portion of the Tx output signal is down-converted using a frequency from a Tx local oscillator.

29. The computer-program product of claim 27, further comprising code for causing the wireless device to amplify a baseband Tx signal using a power amplifier to obtain the Tx output signal.

30. The computer-program product of claim 27, wherein the weight is based on signal gain between the baseband Tx signal and the Tx output signal.

31. The computer-program product of claim 27, wherein the weight comprises a real weight component and an imaginary weight component, and wherein the real weight component is A sin(φ

)/2 and the imaginary weight component is A cos(φ

)/2.

32. The computer-program product of claim 27, wherein the code for causing the wireless device to detect the Tx power level comprises code for causing the wireless device to add together a squared real weight component with a squared imaginary weight component to obtain the Tx power level.

33. The computer-program product of claim 27, wherein the Tx power level is detected using root mean square calculations on the weight

34. The computer-program product of claim 27, wherein the code for causing the wireless device to subtract the reconstructed interference signal from the Tx output signal comprises code for causing the wireless device to subtract the reconstructed interference signal from a baseband Tx signal prior to up-converting and amplifying the baseband transmit signal.

35. The computer-program product of claim 27, further comprising code for causing the wireless device to adjust an output power of the wireless device based on the Tx power level.

36. The computer-program product of claim 35, wherein the code for causing the wireless device to adjust the output power of the wireless device comprises code for causing the wireless device to adjust amplification of a power amplifier.

37. The computer-program product of claim 35, wherein the code for causing the wireless device to adjust the output power comprises:

code for causing the wireless device to match the detected Tx power level to a look-up table; and

code for causing the wireless device to obtain the output power from the look-up table.

38. The computer-program product of claim 27, wherein the reconstructed interference signal and the weight are generated reusing least mean-squared cancellers on the wireless device.

39. The computer-program product of claim 38, wherein the least mean-squared cancellers isolate a desired Tx signal of the feedback signal.

40. The computer-program product of claim 39, wherein the least mean-squared cancellers remove the desired Tx signal from the feedback signal, leaving only noise and interference in the reconstructed interference signal.

41. The computer-program product of claim 27, further comprising code for causing the wireless device to apply a phase shift to the reconstructed interference signal prior to subtracting the reconstructed interference signal from the Tx output signal.

42. A wireless device for Tx interference cancellation and power detection, comprising:

means for down-converting a portion of a Tx output signal to generate a feedback signal;

means for generating a reconstructed interference signal and a weight based on the feedback signal;

means for detecting a Tx power level based on the weight; and

means for subtracting the reconstructed interference signal from the Tx output signal.

43. The wireless device of claim 42, wherein the weight is based on signal gain between the baseband Tx signal and the Tx output signal.

44. The wireless device of claim 42, wherein the means for detecting the Tx power level comprise means for adding together a squared real weight component with a squared imaginary weight component to obtain the Tx power level.

45. The wireless device of claim 42, wherein the Tx power level is detected using root mean square calculations on the weight

46. The wireless device of claim 42, wherein the means for subtracting the reconstructed interference signal from the Tx output signal comprise subtracting the reconstructed interference signal from a baseband Tx signal prior to up-converting and amplifying the baseband transmit signal.

47. The wireless device of claim 42, further comprising means for adjusting an output power of the wireless device based on the Tx power level.

48. The wireless device of claim 42, wherein the reconstructed interference signal and the weight are generated reusing least mean-squared cancellers on the wireless device.

49. The wireless device of claim 48, wherein the least mean-squared cancellers isolate a desired Tx signal of the feedback signal.

50. The wireless device of claim 49, wherein the least mean-squared cancellers remove the desired Tx signal from the feedback signal, leaving only noise and interference in the reconstructed interference signal.

51. The wireless device of claim 42, further comprising means for applying a phase shift to the reconstructed interference signal prior to subtracting the reconstructed interference signal from the Tx output signal.